Epilepsy is a disorder of the brain characterized by recurring seizures, in which there are uncontrolled electrical discharges of brain cells. Epilepsy may arise from a very small area of damaged brain tissue, or from the entire brain. There may be no apparent brain damage, or damage may be limited to an area so small it cannot be detected. Therefore, in nearly one-half the cases, the cause of epilepsy is unknown.
There are several types of seizures associated with epilepsy, the most common of which are generalized tonic-clonic (grand mal), absence (petit mal), complex partial (psychomotor), and elementary partial (focal motor). Each seizure type can be characterized by various symptoms. However, the seizures are generally not life threatening, lasting at most up to three minutes. The exception is status epilepticus, also called continuous seizure state. This is the occurrence of repetitive or continuous seizures and affects approximately 3 to 5% of those individuals suffering from epilepsy. It can exist with all types of seizures and may result in irreversible brain damage or death without prompt medical treatment.
One of the specific problems encountered by parents having children afflicted with epilepsy, particularly status epilepticus, is the problem of alerting the parents when the child may be having an epileptic seizure during sleeping hours. To date the only recourse the parents have is to sleep with the child, in the same bed, hoping to be awakened by the seizure during its early stages when the seizure motion may be quite mild. Often, the parents will choose to supplement this safeguard by using an alarm clock, set to sound every hour, to awaken and observe the state of the child. This, of course, places an extraordinary burden on both the child and the parents and is inherently unreliable. The intermittent sleep afforded the parents as well as the desire for privacy by the child and by the parents make the procedure impractical and inefficient.
Motion sensor devices are obvious solutions to the aforementioned problem, provided that such devices be designed to ignore the casual motions of a sleeping child (rolling over, etc.) while responding to those motions characteristic of a seizure, however mild at the beginning. Existing motion sensor devices such as accelerometers or displacement followers could conceivably be designed to detect certain types of motion while ignoring others, but are invariably expensive and, when the required signal conditioning equipment is included, form a bulky package. Moreover, these devices commonly require electrical connections between the transducer (affixed to the patient) and its associated equipment located near, but not on, the patient.
Accordingly, it is an object of this invention to provide a device for sensing the motion of concern while ignoring, for the most part, other non-harmful motion such as ordinary movement during sleep.
Yet another object of this invention is to provide a simple, effective device for monitoring epileptics without disturbing the sleep of the patient or the observer unless there is a need for concern.
Other Objects will appear hereinafter.